Water is important regardless of diet. The fact is, that generally as a species, we don't drink enough water. We drink liquids that have other contents, many of those ingredients are questionable. And many of those ingredients have a diuretic (sp?) effect - like caffein and alcohol.

If you read up what those wiser than me have posted on ketosis, they say that it is a healthy idea to keep the body hydrated so that waste products move on, more quickly and easily. I could argue that is true regardless of whether or not you are in a state of ketosis.

Water weight gain, is when the body as a whole holds water. This happens when it is dehydrated (not getting enough water), during surges of hormones, and if you engage in certain foods, there is probably an impact with weather and humidity or lack thereof, too.

When you see sudden gains and losses in weight, it can be from water retention issues. It's not possible to lose 3 pounds of fat overnight or gain it.

I weigh myself every night, and can predict with great accuracy what I will weigh the next morning. I normally lose 2 pounds overnight. I will then weigh the same thing I did the morning previous.

If I indulge in bread, or in a salty food (KFC is a good example) I can guarantee that I will be UP 2 pounds the next day.

During my TOM I can gain up to 4 pounds (and that's not much compared to some)

All these are examples are water weight.

The trick is: when you have gained excess water, the best way to get rid of it is to drink water. So when I indulge in salty foods or KFC, or it's my TOM - I drink A LOT of water - it really helps. Otherwise I try to work in a steady 2-3 litres a day minimum.

And the bottom line is, drinking a steady and appropriate amount every day WILL contribute to weight loss. Drinking a lot one day and then little for the next 2 days, etc etc, just makes your body believe you are living in the desert and are moving from oasis to oasis - so it's going to try and hold onto the water it has. Make your body believe that water is plentiful and never ending, and it will be less likely to retain any.

Inital weight loss may be partially a loss in water, but that is water retained from being on a high carb - low fat diet. It's water your body didn't need, it was just hanging onto it because of the diet you were on previously.